The present invention relates to a device for controlling the operation of a carburetor.
In a conventional engine, the increase in the temperature of the engine cooling water corresponds to the progress in engine warm-up. Consequently, in the majority of conventional engines, engine operation is controlled during engine warm-up in accordance with the change in the temperature of the engine cooling water. For example, a carburetor control device has been known in which the fast idle cam of the carburetor is actuated by a wax valve which is operated in response to the change in the temperature of the engine cooling water.
The reason why the engine cooling water is used for controlling engine operation during engine warm-up in the majority of conventional engines is that the engine cooling water is easier to handle than engine lubricating oil and electrical control devices and the construction of the engine control device can be simplified.
Newer engines, however, are being designed for reduced weight, one method of reducing weight being to reduce the amount of cooling water as much as possible. In such newer engines, the cooling water temperature increases faster during engine warm-up than in conventional engines. Thus, the increase in the cooling water temperature no longer corresponds to the progress of engine warm-up. If such a newer engine is equipped with a conventional carburetor designed so that the fast idle cam thereof is actuated in response to the change in the cooling water temperature, the fast idle cam will become disengaged from the throttle valve of the carburetor before the completion of engine warm-up. The engine speed will therefore drop and the engine will stop.